The Supreme Court on Thursday declined to reinstate an effort by President Obama to provide relief from deportation to millions of undocumented immigrants.

The Obama administration has sought to offer some undocumented immigrants a guarantee that they would be allowed to stay in the United States temporarily. The president has done so in two stages. In 2012, he allowed undocumented immigrants brought to the United States at a young age to apply for a temporary reprieve from deportation. Then, in 2014, he expanded on the policy by including older undocumented immigrants who had come as children, as well as the undocumented parents of U.S. citizens.

With their victory in court, Republicans have now successfully stymied the second of those expansions. They view Obama's policy overall as a kind of amnesty that the president does not have the authority to grant.

Yet their victory was not as complete as it might have been if not for Antonin Scalia's death earlier this year. His passing left the court with four liberal and four conservative justices, who were divided evenly on the decision. The deadlock upheld the decisions of lower courts that ruled against Obama but rendered the Supreme Court unable to establish a decisive precedent for future cases.

Here's a closer look at the immigrants whose futures the justices decided Thursday.

How many people are affected by the Supreme Court's decision?

The plan Obama put forward in 2014 would have offered relief to two broad categories of undocumented immigrants.

The first would have included parents whose children who are citizens or legal permanent residents. There are about 3.6 million people in this group, according to estimates from the nonpartisan Migration Policy Institute. Many of them came to the United States illegally but are the parents of citizens because their children were born here. Together with their families, according to the institute, there are at least 10 million people (including legal immigrants, citizens and undocumented immigrants) who live in households that would have been affected by this rule.

The second group would have included the immigrants who were brought here illegally as children and were not granted a reprieve under the 2012 action. The 2014 proposal would have expanded that group by 300,000 to include older immigrants and more recent arrivals. The statuses of the 1.2 million who already applied under the policy from 2012 are not affected by the Supreme Court's ruling Thursday.

The following chart breaks down the 4 million people, in total, who would have been granted reprieve under Obama's plan but were denied protection by the court.

Who exactly is affected?

Most undocumented immigrants would not have been eligible for a reprieve even if the court had allowed Obama's plan to proceed. Their statuses are not affected by the ruling. At the same time, many immigrants met the specific requirements of Obama's plan might have hoped that the court would agree to grant them relief.

For the parents of citizens or legal permanent residents, their children would have to have been born before Nov. 21, 2014 -- the date of Obama's recent executive action -- and the parents would have to have been in this country the day before. They also would have to have lived in the United States since at least Jan. 1, 2010, and they'd have to pay taxes to win the reprieve.

For children brought here illegally, they must have arrived before Jan. 1, 2010 and before their 16th birthdays. They also would have to be in school, have graduated or earned a GED or have been honorably discharged from the military.

The diagram below illustrates which immigrants would have been eligible for a reprieve from deportation if the Obama administration had won its case. Although the administration lost the argument, most immigrants who arrived as children would still be eligible under the 2012 policy.

What will the court's decision mean in practice?

The decision Thursday effectively takes the bulk of Obama's immigration agenda off the table for the rest of his presidency. The implications for the future are unclear, however. Since the case ended in a deadlock, with the justices on the court evenly divided, the decision will not have the force of precedent as cases that are decided by a majority. As is customary in such cases, the court was constrained to issuing an opinion of just a single sentence, with no discussion of the fundamental legal issues.

The rulings in the case so far have been preliminary, and the parties will next argue the merits in district court. If Hillary Clinton wins the presidential election in November, her lawyers would presumably continue contesting the issue, or she could put a similar plan of her own forward. After appointing a more liberal justice to the Supreme Court to replace Scalia, she might receive a more favorable ruling once the court is restored to its full complement of justices.

That is just speculation, of course -- Donald Trump, the presumptive Republican nominee, could also win the presidential election, or Congress might address the question of immigration separately.

Obama's plan would not only have granted immigrants permission to stay in the country temporarily without papers. They could have also applied to work while they were here, meaning they would have been able to earn more money for their families. They would not have been limited only to employers who overlook fraudulent or nonexistent immigration paperwork, and they could have found jobs that better suit their skills.

Immigration is one of the hottest issues in the 2016 election. But it wasn't always at the front of the policy conversation. The Fix explains what changed, and why it matters this year. (Peter Stevenson/The Washington Post)

According to a recent report that the Migration Policy Institute published together with the Urban Institute, a typical family with parents eligible under the president's plan because the children are citizens or permanent residents would have earned about $3,000 more per year on average under Obama's plan. Their incomes would have increased by 10 percent, in other words.

The authors of the report accounted for differences in immigrants' age, education and proficiency in English, among other factors. Examining the families in this group that are currently living in poverty, the researchers concluded that one in six would no longer be poor if they were allowed to work. The court's decision rules out those increases in income, at least for now.

This post has been updated from an earlier version published after the Supreme Court heard oral arguments in the case.